A catheter includes an elongated catheter body adapted to be inserted, for example, into a vein or an artery for various medical purposes. The catheter body has one or more lumens, and each of the lumens is adapted to perform a different function. For example, the lumens may carry conductive leads, provide for inflation and deflation of a balloon, carry medication or other substances for infusion into the patient, sample body fluids, or be used in the measurement of blood pressure or the like. Because each lumen performs a different function, it is common practice to couple each of the lumens to different locations or connectors with extension tubes.
One common way to couple the extension tubes to the proximal end of the catheter body would be to bond the extension tubes to a plastic adapter which in turn is bonded to the catheter body. This technique is very labor intensive and requires long staging times for drying of the adhesive. In addition, the adhesive may flow into one or more of the lumens and cause a partial or complete blockage.
To eliminate the bonding, wire mandrels can be inserted through each of the extension tubes and into the associated lumen of the catheter body. A coupling body can then be injection molded around the extension tubes and a proximal portion of the catheter body to join the extension tubes to the catheter body. The mandrels are then removed to provide passages in the coupling body leading from the extension tubes to the associated lumens.
Unfortunately, this molding process is unable to accommodate the normal tolerance variations in outside diameters of the extension tubes and catheter body. Consequently, relatively large diameter extension tubes or catheter bodies tend to melt in the mold, and the relatively small diameter extension tubes and catheter bodies permit the plastic being injection molded to "flash" out of the mold along the outside of the extension tubes and/or catheter body. In addition, contacting the hot plastic used for injection molding directly onto the catheter body and extension tubes tends to cause kinking or lumen collapse during normal use of the catheter. Finally, this technique required a separate mold for each catheter having a different number of lumens.